For specified buildings such as commercial facilities or offices with site areas of 3000 [m2] or more, it is prescribed by the Building Sanitation Control Law to keep indoor temperature at 17[° C.] to 28[° C.], and relative humidity at 40[%] to 70[%] as control standard values for the air environment. Of these, indoor temperature is controlled relatively easily with the proliferation of air-conditioners. However, it is hard to say that relative humidity is sufficiently controlled. In particular, lack of the amount of humidification in winter time has become a problem.
Conventional indoor humidification methods include evaporative, steam, and water spray methods. Among these, the evaporative method is a method of passing air through a filter having water absorption capability to cause moisture contained in the filter to exchange heat with an airstream, thereby evaporating the moisture to perform indoor humidification. The steam method is a method of energizing a heating coil placed inside a water reservoir to evaporate moisture, thereby performing indoor humidification. The water spray method is a method of atomizing moisture by pressurization, and causing the atomized moisture to exchange heat with an airstream to thereby perform indoor humidification.
As a conventional humidifier using a porous electrode, there has been disclosed a sprayer that employs, for the purpose of mist generation, a spray method using corona discharge in which an annular electrode is disposed around a position where the fluid to be sprayed is ejected, and the fluid is explosively dispersed to generate fine mist (see, for example, Patent Literature 1).
Also, an air humidifier has been disclosed in which a porous plate-like body made of sintered SiC and having a three-dimensional porous structure is arranged in an air passage in such a way that its broad surface side is oriented substantially perpendicularly, a water supply pipe is arranged in contact with the upper surface of this porous plate-like body in such a way that the entirety of an inorganic fiber layer is impregnated with water, a water receiver is provided below the porous plate-like body in such a way that a lower part of this plate-like body is beneath the surface of water, and an electrode for passing electric current through this plate-like body are attached at either side of the porous plate-like body (see, for example, Patent Literature 2).